Emulsions and process of making the same



Patented Nov. 8, 1938 UNHTED STATES PATENT GEFECE Parke Lowe Boneysteele and Manford Lemuel McKercher, Baltimore, Md., assignors to American Bitumuls Company,

San Francisco,

Calif., a corporation of Delaware No Drawing. Application August 12, 1932, Serial No. 628,550

11 Claims.

The invention relates to the production of emulsions of the oil-in-water type in which mineral oils, waxes,'natural or synthetic resins, vegetable oils, am'mal oils, bituminous substances or the like are dispersed in an aqueous medium for use as binders, waterproofing and impregnating agents, paints and the like.

The invention particularly relates to aqueous bituminous emulsions of asphalt or pitchy binder capable of being readily mixed with aggregates, fillers and fibrous materials in the manufacture of pavements, briquets, compounds and structures in which discrete particles are bound together by closely adherent films of bituminous binder whereby they may be laid or formed into coherent and solid masses, and to emulsions of like character suitable for application to surfaces by brushing or spraying to produce waterproof or otherwise protective coatings.

The term aggregates, fillers and fibrous materials embraces a variety of materials such as crushed rock, stone, brick, slag or other broken or granular mineral, sand, pumice, coal particles or other carbonaceous substances, asbestos, mineral wool, wood or other paper pulp, cork chips and the like. The materials bound together with bituminous binder may be compacted to form as in pavement construction or they may be compressed into briquets, blocks or other shapes or rolled into sheets as desired.

Heretofore commercially obtainable bituminous emulsions have been employed in this manner, such emulsions bein generally termed either quick-breaking or slow-breaking emulsions. Examples of quick-breaking emulsions are those described in United States Patent No. 1,737,491 to Carl Alfred Braun and United States Patent N 0. 1,643,675 to James A. Montgomerie, in the manufacture of which no emulsifiers other than alkaline water are added. Such emulsions, although generally highly fluid, when mixed with cold dry aggregates or applied as paint tend to break rapidly and form agglomerated masses without properly coating the surfaces.

Slow-breaking emulsions are well known in the art and may be prepared with the aid of numerous emulsifying agents such as soap, clay or casein. They are generally stable as compared with emulsions of the quick-breaking type, and while the tendency toward breakdown or agglomeration is not so pronounced, they are usually pasty in texture or highly viscous and require dilution before they can be practicably employed for the purposes described.

Therefore it may be seen that with emulsions of equal bitumen content, the quick-breaking type tends to break down or agglomerate on contact with aggregates and the slow-breaking emulsions offer difficulties in incorporation with aggregates or in application to surfaces by reason of trolling the rate of setting or drying of bituminous emulsions when mixed with aggregates or applied to surfaces.

Another object is to develop a method of treating bituminous emulsions unsuitable for mixing with aggregates or applying to surfaces whereby they are rendered adaptable to such purposes.

Other objects of the invention will be apparent from the following description of the process and examples of methods employed in putting it into practice.

It has been discovered that quick-breaking bituminous emulsions of the type described may be rendered substantially slow-breaking by treatment in accordance with the invention, and it has been found that the drying or setting time of such emulsions may be so altered by the treatment, that the emulsions may be readily mixed with aggregates or applied to surfaces without premature break-down or agglomeration.

For example, tri-sodium phosphate in an amount equal to of one percent based on the emulsion was introduced in water solution into an aqueous emulsion of asphalt prepared by the Braun process described in United States Patent No. 1,737,491 in which no emulsifying agent other than alkaline water is added during the manufacture. The emulsion to which the trisodium phosphate was added was completely formed at the time of the addition and was in practically cold condition, i. e., of a temperature lower than 100 F. It was found that while the fluidity of the emulsion was substantially unaffected, its character was otherwise changed so that it was capable of mixing with aggregates or applying to surfaces without premature breakdown or agglomeration.

The underlying reason for this unexpected change in the character of the emulsion is not known, but the result seems to follow the addition of tri-sodium phosphate to the practicallly cold finished emulsion as described, as similar results were not obtained when tri-sodium phosphate was. added to the hot materials undergoing emulsification or employed as a primary emulsifying agent in the preparation of the emulsion.

It has also been discovered that slow-breaking emulsions in which soap or saponaceousmaterial is employed as an emulsifying agent, may be altered in their viscosity characteristics, and their setting, drying and mixing properties, retained, restored or controlled by treatment in accordance with the process of the invention.

For example, an emulsion prepared by emulsifying molten asphaltby means of a solution of rosin oil soap, and containing about 65 percent asphalt was found to have a viscosity Furol of approximately 3900 seconds, whereas by treatment in accordance with the process of the invention and without materially affecting the proportion of asphalt or soap the viscosity of the same emulsion could be reduced below 500 seconds or even as low as 40 seconds Furol without substantial impairment of the mixing and drying properties of the emulsion.

In the practice of this phase of the invention it is contemplated that a solution of salts or acids tending to precipitate the emulsion or capable of forming insoluble compounds with a component of the aqueous phase thereof shall be added to the emulsion after it has been prepared in the cus tomary manner, followed immediately by a solution of a stabilizing substance, the first addition being for the purpose of reducing the viscosity of the emulsion and the second, to render the emulsion slow-drying or slow-setting as required for the uses in which it is to be employed.

It is believed that the addition of the salt or acid solution so changes the character of the ordinarily slow-breaking soap-type emulsion that it becomes essentially a quick-breaking non-viscous emulsion, and that the addition of the stabilizing substance restores the slow-breaking characteristics of the emulsion without restoring its original high viscosity so that a highly fluid emulsion having the desired drying or setting properties is produced.

It has been found that solutions of the salts of alkaline earth metals such as calcium chloride or magnesium chloride are suitable for the purpose of imparting fluidity or reducing the viscosity of such emulsions, and that tri-sodium phosphate solution is well adapted to restore or produce the desired drying and setting properties.

Other substances functioning in a like manner in a greater or less degree may be substituted for the alkaline earth salts or the tri-sodiurn phosphate as will be evdent to those familiar with the art. As an example to facilitate the carrying out of the process of this phase of the invention, the following may be cited:

A soap solution was prepared by saponifying 9 parts by weight of Swedish rosin oil with one part of caustiosoda in 15 parts of water. To 7 parts of this soap solution were added 65 parts of molten asphalt with intimate mixing until emulsification was effected. To the emulsion thus obtained was added by titration an aqueous solution of 13.? parts of water and 0.154 part of anhydrous calcium chloride with thorough agitation until the mass became homogeneous. Immediately thereafter a second aqueous solution containing 13.7 parts of water and 0.169 part of anhydrous tribasic sodium phosphate was added and agitation continued until the mass again became homogeneous. An extremely fluid emulsion, viscosity seconds Saybolt Furol or below, was produced having excellent drying and setting properties, and

capable of being mixed with aggregates or applied to surfaces without premature breakdown. An emulsion containing similar proportions of asphalt, soap and water but no calcium chloride or sodium phosphate. was found to have a viscosity of about 4000 seconds Saybolt Furol.

It was further found that when the process was carried out substantially as described it was possible to produce emulsions of a given bitumen content with almost any desired combination of viscosity and breaking or setting characteristics by varying the proportions of calcium chloride and tri-sodium phosphate. The more calcium chloride used the more the viscosity was reduced while increasing the amount of 'tri-sodium phosphate increased the slow-breaking characteristics of the emulsion.

It is obvious that, since calcium chloride has long been recognized as a breaker or inverter for oil in water emulsions containing a water soluble soap as primary emulsifier and since complete break down or inversion is entirely inconsistent with the expressed objects of the present invention, amounts of calcium chloride sufficient to cause break down or inversion must be avoided.

It will also be recognized by those skilled in the art'that since the amount of calcium chloride necessary to bring about inversion is a function of the nature of the bitumen used, or the kind and amount of soap employed as primary emulsifier and of the desired bitumen content of the finished emulsion, no specific limits of concentration can be given. An entirely similar situation exists with respect to the tri-sodium phosphate; the amount necessary to produce a finished emulsion of any given setting or drying properties will depend on the factors just enumerated and, in addition, on the amount of calcium chloride necessary to give the desired viscosity in the finished emulsion;

The foregoing example must therefore be regarded as entirely illustrative and with no limiting effect upon the appended claims.

It will be apparent to those familiar with the art that the method of producing emulsions of high bitumen content and with viscosity and drying and setting properties controllable at will,

Will greatly facilitate the use of emulsions in the practice Of road building, aggregate impregnation, saturation of materials, painting and the like.

Thus in constructing a penetration type macadam pavement where it is customary to apply the binding medium to road materials or aggregates in place, by means of pressure distributors, hand sprayers and the like, it is obvious that an emulsion so used must be sufliciently free flowing and slow-setting to permit of its being handled by the customary equipment, and to permit of its providing a proper film of binder on the aggregates.

Then in the manufacture of asphaltic concrete where aggregates are mechanically mixed with binders, an emulsion so used must be of sufficient viscosity to insure that an adequate film of binder is placed on andcremains on the surfaces of the aggregates and the rate of setting or drying should be retarded sufficiently to permit of the coated material being transported from the place of mixing to the point of use without premature breakdown.

Again, in the paint industry an emulsion must be of sufficient fluidity to permit of its being brushed or sprayed on surfaces being treated, and sufliciently slow-drying and. slow-setting so as not to ball up under the brush or otherwise break down into its constituents before the surfaces to which it is applied are properly coated.

Again, certain waterproofing and roofing operations require a plastic, viscous emulsion capable of being trowelled or plastered in place.

While particular methods, materials and. proportions have been described in order to illustrate the process of the present invention, the invention is not intended to be limited thereby, but to embrace all variations and modifications within the scope of the following appended claims.

We claim:

1. A process for the production of fluid bituminous emulsions of mixing grade which comprises the step of adding trisodium phosphate to a low viscosity, quick-breaking clay-free emulsion which is primarily dependent for its formation, stability and setting characteristics upon the interaction of saponifiable constituents of the bitumen with an aqueous alkaline medium in which it is dispersed, said addition being in amount sufficient to render the emulsion slow-breaking to the point that it may be mixed with aggregates, fibrous fillers and the like without premature breakdown resulting in agglomeration of the bitumen into lumps.

2. A process for the production of fluid bituminous emulsions of mixing grade as in claim 1 wherein the addition of trisodium phosphate is effected at a temperature less than about 100 F.

3. A process for the production of fluid bituminous emulsions of mixing grade as in claim 1 wherein the amount of trisodium phosphate added is less than about of one percent by weight of the emulsion.

4. A process for the production of fluid bituminous emulsions of mimng grade as in claim 1 wherein the amount of trisodium phosphate added is less than about of one percent by weight based on the emulsion and the addition is effected at a temperature less than about 100 F.

5. A process for the production of fluid bituminous emulsions of mixing grade which comprises the step of adding trisodium phosphate to a lowviscosity quick-breaking emulsion resulting from i the treatment of a fatty acid soap emulsified product with a water soluble salt of an alkaline earth metal, said addition being in amount sufficient to render the emulsion slow-breaking to the point that it may be mixed with aggregates, fibrous fillers and the like without premature breakdown resulting in agglomeration of the bitumen into lumps.

6. A process for the production of fluid bituminous emulsions of mixing grade as in claim 5 wherein the amount of trisodium phosphate added is less than about of one percent by weight of the emulsion.

'7. A process for the production of fiuid bitumi nous emulsions of mixing grade as in claim 5 wherein the amount of trisodium phosphate added is about 0.17 percent by weight of the emuls1on.

8. A process for the production of fluid bituminous emulsions of mixing grade which comprises the steps of converting a viscous, relatively slowbreaking emulsion, which is primarily dependent for its formation, stability and setting characteristics upon the presence of a substantial proportion of a water soluble fatty acid soap, into a fluid, quick-breaking product of substantially the same bitumen to water ratio by adding thereto a water soluble salt of an alkaline earth metal in amount less than required to efiect appreciable demulsification followed immediately by the step of contributing mixability with aggregates and the like through the addition of trisodium phosphate in controlled amount.

9. A process for the production of fluid bituminous emulsions of mixing grade having viscosity and setting time independently regulated while maintaining a substantially constant ratio of bitumen to water as in claim 8 in which the water soluble alkaline earth salt added to effect viscosity reduction is calcium chloride.

10. A process for the production of fluid bituminous emulsions of mixing grade having viscosity and setting-time independently regulated while maintaining a substantially constant ratio of bitumen to water as in claim 8 in which the water soluble alkaline earth salt added to effect viscosity reduction is magnesium chloride.

11. A process for the production of fluid bituminous emulsions of mixing grade having viscosity and setting-time independently regulated while maintaining a substantially constant ratio of bitumen to water as in claim 8 in which calcium chloride is added in amount less than about 0.2 percent followed by trisodium phosphate in amount less than about 0.5 percent, both by weight of the emulsion.

PARKE LOWE BONEYSTEELE. MANFORD LEMUEL MCKERCHER. 

